Highly reactive polycondensates, especially thermosetting plastics, are produced in batch operations in reactors. After extrusion from reactors, the synthetic resin plastics are cooled with water in order to obtain certain required and desirable product qualities with respect to the physical characteristics of the synthetic resin plastic. By cooling with water, further reaction of the synthetic resin is stopped. The normal procedure is then to collect the synthetic resin issuing from the reactor in large troughs and cover it with cooling water. After the cooling, the water is let out, and the resin removed manually. Then, it is dried and milled.
This milled synthetic resin is fairly hard and brittle, but is not yet finally set. By raising the temperature once again, it becomes soft and fusible again for a short time before hardening finally and irreversibly. Thus, these types of synthetic resins are employed as bonding agents for molded articles, coatings, and other industrial goods, for example, the linings for brakes. The characteristic for tempering of synthetic resin plastics is the B-time or period. It expresses the time of reaction for a synthetic resin plastic, at a certain temperature and under momentarily existing conditions, to pass to the B-state (see DIN 16916 T1). This B-time, of course, is quite short, however, it is not a preliminarily determinable constant. Indeed, it fluctuates over about 2 min. within a given batch. For the purpose of further processing into molded articles, an advantageous plastic is one with negligible fluctuation in its B-time, inasmuch as a uniform setting or hardening will give rise to products which are qualitatively of higher value.